torpedo boat

torpedo boat, small fast warship built specially for using the torpedo as a means of attack. The first modern torpedo boat was the Lightning, built for the British navy in 1877 by the shipyards of Sir John Isaac Thornycroft. Torpedo boats were adopted by most of the world's major navies, but as they increased in size the destroyer was developed as an effective defense against them. They diminished in importance after the Russo-Japanese War (1904–5) and were used sparingly in World War I, but they were widely employed in World War II. At that time torpedo boats, often referred to as PT boats, were commonly used in attacking enemy coastal shipping and light naval forces under cover of darkness and bad weather. They were usually wooden vessels 75 to 125 ft (22.8–38.1 m) long, powered by gasoline or diesel engines and capable of very high speeds.